Pre-Analytical Errors and Specimen Hemolysis
The quality of a laboratory result is only as good as the quality of the sample. The most common pre-analytical error associated with vacuum tubes is hemolysis—the rupture of red blood cells. When cells rupture, they release their internal contents, such as potassium and hemoglobin, into the surrounding liquid.
Hemolysis often occurs due to improper technique rather than tube failure. Common causes include:
Using a needle that is too small (causing high-pressure shearing of cells).
Vigorously shaking the tube instead of gentle inversion (standard is 5–10 slow inversions).
Pulling blood through a catheter or "butterfly" set too forcefully.
Excessive heat or cold during transport. Laboratory technicians must reject hemolyzed samples because the released potassium can lead to a "pseudo-hyperkalemia" result, potentially causing a doctor to prescribe unnecessary and dangerous treatments.